System and method for computer aided dispatching using a coordinating agent

ABSTRACT

A system and method for controlling the movement of plural trains over a rail network, where the rail network is divided into a plurality of planning areas with a boundary element of common track between adjacent planning areas, using a local coordinating agent for controlling the movement of the trains through the boundary elements.

This application claims the benefit of U.S. Provisional Application60/449,849 filed on Feb. 27, 2003, and is related to commonly ownedpatent application titled “System and Method for Dispatching byException”, filed on even date, herewith, both of which are incorporatedby reference.

BACKGROUND

The development of a train schedule for a global rail network, i.e.,nationwide, is difficult on a real time basis due to the complexity ofthe problem of controlling many trains competing for limited resourcessimultaneously. Rail networks typically contain tens of thousands ofmiles of track, thousands of locomotives and hundreds of thousands offreight cars. At any one moment, thousands of trains and maintenancevehicles may be competing for a limited amount of track. To manageconsistent scheduled service in this environment, railroads use the“divide and conquer” technique to partition the railroad network intoseveral control territories and generate a local movement plan for eachcontrol territory to thereby distribute the complexity of the schedulingproblem over many scheduling resources. Human train dispatchers areassigned to these control territories, and have the responsibility tosmoothly transit trains and equipment across the control territory, withminimum delay in accordance with the corresponding movement plan for thecontrol territory. Multiple dispatchers, each controlling a predefinedportion of the railroad, comprise the paradigm for modern daycomputer-based railroad dispatching systems.

In this environment, the dispatcher is expected to solve complexmovement problems in real time. For example, dispatchers must considerthe limited track resources, length of trains, length of availablesidings, train meet and pass points, maintenance requests for tracktime, engine availability, etc. Dispatching can become a stressfulenvironment, and while safeguards are in place with signaling systems inthe field, dispatcher mistakes could cost lives and frequently resultsin significant decreases in performance for the railroad To ease theburden, computer processing scheduling systems are used to helpdispatchers “see” their control area, and external systems provide aconstant flow of information about the state of the railroad. Thisinformation flow includes train schedules, customer commitments,maintenance schedules, train consists, track outages, crew information,weather and other dynamic factors that directly affect the dailyoperations of the railroad. As more systems are computerized,dispatchers receive more accurate information, however; the volume ofinformation is growing at a rate that makes it increasingly difficult toformulate decisions and actions in real time. Because of informationoverload, and the decision structures of typical dispatch systems,dispatchers lack insight into effects of their actions on the entireroute of the train, or the effects to the railroad as a whole. Severaltrain dispatchers will “touch” a train as it traverses its route acrossthe railroad network. With limited information and a predefined decisionstructure, it is inevitable that one dispatcher's action, whileappropriate within the context of the dispatcher's territory, results inlarge financial losses for the railroad.

Without full comprehension of the complex adjacent territories or therelative value of a train to the railroad at any one particular instant,the dispatcher is ill equipped to make optimum dispatch decisions, evenwithin their control own territory. As such, a dispatcher may route atrain into an adjacent territory, only to discover that by doing so, theend result is more congestion for the overall railroad. In this instancethe correct decision would have been to hold the train within thedispatcher's territory at an available siding or yard with amplecapacity, and wait until the congestion reduces or clears. Anothersituation in which the dispatcher lacks adequate information about theglobal network to make the most optimal decision may occur where severaltrains need to pass through a congested track area, and there is notenough available track to accommodate all simultaneously. The dispatcherhas to quickly decide which trains to “side” (place in an availablesiding) in order to let other trains pass. In today's dispatchingenvironments, there is insufficient information about a train in contextwith all other trains in other control territories in order for thedispatcher to make the best decision for the railroad as a whole, due tothe lack of coordination of the movement of trains from one controlterritory to an adjacent control territory.

The present application is directed to a system and method of schedulingand controlling the movement of trains over a large rail network.According to one aspect of the invention, the rail network is dividedinto a plurality of planning areas as a function of the shared resourcesbetween each adjacent planning area.

According to another aspect of the present invention, a local movementplan for each planning area develops a local movement plan independentlyof the movement plan developed for other planning areas to control themovement of trains into and out of the shared resources associated withthe adjacent planning areas.

According to yet another aspect of the present invention, each of thelocal movement plans is evaluated to identify conflicts at the sharedresources between adjacent planning areas.

According to still another aspect of the present invention, the localmovement plans are modified to resolve the identified conflicts at theboundary elements.

The advantages of the present invention will be readily apparent to oneskilled in the art to which it pertains from a perusal of the claims,the appended drawings, and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified pictorial representation of a rail networkdivided into plural planning areas in accordance with one embodiment ofthe present invention.

FIG. 2 is a simplified functional block diagram illustrating theinteraction between a local coordinating agent (LCA) and adjacent localplanning agents (LPSs) for use with the embodiment of FIG. 1.

FIG. 3 is a simplified pictorial representation of a boundary element inaccordance with one embodiment of the present invention.

FIG. 4 is a simplified pictorial representation of a boundary element inaccordance with another embodiment of the present invention.

FIG. 5 is a simplified pictorial representation of a boundary element inaccordance with yet another embodiment of the present invention.

FIG. 6 is a simplified timeline illustrating the scheduled usage of aboundary element in accordance with one embodiment of the presentinvention.

FIG. 7 is a simplified timeline illustrating the scheduled usage of aboundary element in accordance with one embodiment of the presentinvention.

FIG. 8 is a simplified functional block diagram of one embodiment of aconflict resolution module for use with the embodiment of FIG. 2.

DETAILED DESCRIPTION

The coordination of the movement of trains from one control territory toanother is important to the development of an achievable global movementplan. However, the selection of boundaries of prior art of controlterritories contributes to the problems identified above. Instead, ifthe boundaries of a planning areas were selected as a function of thetrack characteristics and the movement of trains through the sharedresources were carefully controlled, the complexity of the trainmovement scheduling and the attendant problems identified above would begreatly reduced.

FIG. 1 illustrates how a global rail network can be partitioned into aplurality of planning areas 10 where each planning area shares at leastone resource, known as a boundary element 20, in accordance with oneembodiment of the present invention. The boundary elements are selectedas a function of the configuration of the track elements 22 which arecommon to adjacent planning areas and takes into account suitablefactors, such as the miles of track, track complexity and anticipatedtraffic in the planning area. Thus the boundaries of the local planningareas are defined by the selection of boundary elements 20, which mayresult in an irregular shape of the planning areas. A real-time solutionto the scheduling problem can be achieved by closely controlling thepassage of the trains through the boundary elements, while allowing thedispatcher to otherwise control the movement of the trains under hisresponsibility in his planning area which is configured independently ofthe boundary elements.

In one aspect of the present invention, a computer processor based LocalPlanning Agent (“LPA” also designated at 23) is assigned to eachplanning area. The LPA generates a local movement plan (“LMP”) tocontrol the movement of the trains in the corresponding local planningarea. Each LPA operates independently and asynchronously from all otherLPAs. Adjacent LPAs provide their respective LMPs to a computerprocessor based local coordinating agent (“LCA” also designated at 21).The LCA 21 has the responsibility for managing the movement orderconstraints for the boundary element 20, i.e., the order (sequence) ofthe trains and the ranges of times of arrival and departure for thetrains through the boundary element. While the LPA 23 controls themovement of trains in its respective local planning area, the LPA 23 isconstrained to maintain the order of arrival and departure of trainsthrough a boundary element 20 that is determined by the LCA 21. Asdescribed below, each LCA 21 includes a boundary element usage module26, a conflict detection module 27, a conflict resolution module 28 anda train movement timing and sequencing module 29. The modules may be acomputer readable program code embodied in a computer usable medium foruse with a general purpose computer.

FIG. 2 illustrates the relationship between a LCA 21 for boundaryelement 20, and the local planning agents 23 for adjacent planning areas10. Each LPA 23 independently and asynchronously generates a LMP 24 andsends its LMP to the LCA 21 for the respective boundary element 20 forreview. For each train in the LMP 24, the LPA provides information onthe status of the trains planned movement through the boundary element.While the train is a long time from arriving at the boundary, the statusis marked ‘Planned’. As a train approaches the boundary (<8 hours away)the status changes to ‘Resolved’ (a firm plan is in place), or‘Unresolved’ (the trains plan is not firm because a conflict withanother train within the LPA has not been resolved). As a train nearsthe boundary element, typically 30-60 minutes away, the movement planacross the boundary will be marked as ‘Committed’, meaning that the LPAmay not make any further adjustments to the plan. As the trainapproaches the boundary element control signals are cleared or trackwarrants issued by the traffic control system and the train is marked‘Authority Issued’. Once track authority is issued to a train neitherthe LPA's or the LCA's can change the plan for the trains movement. TheLCA 21 reviews each LMP and identifies planned usage of the boundaryelement at the boundary element usage 26 and the status of the trainsplanned movement as discussed above. If a conflict between the usage ofthe boundary element is detected at the conflict detection module 27(e.g., overbooking of the trains set to pass through the boundaryelement), the LCA 21 resolves any conflict in the LMPs for the LPA 23 inthe conflict resolution module 28. The conflict resolution module 28considers the boundary element availability (movement may be restrictedduring certain periods for track maintenance, etc.), train arrivaltimes, train dwell time (trains may have scheduled work on the boundaryelements), and the cost of delaying a train (based upon a cost functionkeyed to the trains arrival at a predefined waypoint). In addition, theLCA considers a congestion metric supplied by the LPA's to providebackpressure in the event that congestion is building up within one ofthe planning areas. The conflict resolution module defines the trainsequence for moves at the boundary elements 20, and provides the trainmovement timing and sequencing module 29 updated estimated times oftrain arrival, dwell time and sequence that are passed to each of theadjacent LPAs 23 in order to update their respective LMPs. Therespective LPAs 23 use these inputs in their next planning cycle. Theresult of the process is that conflicts in plans at the boundary becomesmaller as a train moves toward the boundary element and by the time itis ‘committed’ the conflicts have been resolved and the LMPs will agreeat the boundary element.

Because each boundary element appears in two LPAs, the trains that willoperate in both LPAs must be coordinated at the boundary element 20. Forany given update to a LMP by one LPA, the occupancy times (entry andexit) of a train in the boundary element used for a common track 22 maynot necessarily coincide with the boundary element occupancy times ofthe same train set by the LMP of the adjacent LPA 23, because each LPAoperates independently and asynchronously with respect to the otherLPAs. Thus, it is necessary for the LCA 21 to coordinate the boundaryelement usage by both trains in order to compile a correct estimate ofthe boundary element usage. For each boundary element, the respectiveLCA will compare the boundary element usage of a newly generated LMPfrom one LPA with the existing LMP of the adjacent LPA. If the boundaryelement is overbooked, the LCA 21 will generate a schedule of resourceusage that removes the overbooking and provides appropriate constraininginputs to the cognizant LPA. The cognizant LPA use these constraints inits next plan generation cycle. In addition, a LCA 21 will specify theordering of trains through a boundary element. The LPAs will honor thisordering in the next plan generation cycle.

Inputs 25 to the LCA 21 may include business objective functions foreach of the trains, the capacity of the boundary element, andconstraints on occupancy times. The business objective function for eachtrain is used to evaluate the incremental cost of delaying each train.Evaluating the incremental cost at the boundary element allows the LCAto compare the value of alternatives in assigning the trains toavailable time intervals at the boundary element.

The capacity of a boundary element is the number of trains that can bepresent at the boundary element at any instant of time. If the boundaryelement is a single segment of track (one signal block) then thecapacity is one. In some areas, however, longer or more complex trackmay allow more than one train into a boundary element at the same time.The planned usage of the shared boundary element is the sum of thescheduled usage of the boundary element by each of the LPAs. This usageis derived from the LMPs for each of the trains planned through theboundary element within the planning horizon.

Train occupancy constraints identify a train occupancy that must behonored by the LCA. This constraint allows a user to select and “freeze”the occupancy time for a train or a LMP to be frozen because trackauthorities have already been issued to the train. It also provides ameans for specifying temporary reduction of boundary element capacitybecause of maintenance of work (MOW) or other constraints. Mutuallyexclusive constraints specified in a LMP will result in a planningexception that must be resolved by dispatcher action.

Based on a consideration of each of the inputs, a LCA will outputmovement order constraints and the sequence in which trains will movethrough the boundary element. The LCA provides movement orderconstraints specifying the availability of a boundary element for eachof the cognizant LPAs. This availability restricts a LPA from utilizinga boundary element during a time interval that has been reserved for itsadjacent LPA. Constraints are implemented by specifying the ETA anddwell time (i.e., the time a given resource is in use and not available)at the boundary element for trains from the adjacent planning area. Eachreservation period may include a cushion to reduce the impact of smallarrival time fluctuations.

The train sequence outputted by the LCA provides an ordering for trainsto move through a boundary element. The LPAs honor this ordering. Trainsequence is not binding on the next replan by the LCA, unless theassociated plan status is ‘authority issued’.

The local planning areas do not have to correspond with the prior artcontrol territories associated with a human dispatcher. The planningareas can encompass several control territories under the control ofindividual dispatchers; each dispatcher having responsibility forexecution of a portion of the LMP. Boundary elements may occur atlocations where the track is controlled or not controlled. Uncontrolledtrack is track that is not controlled by the dispatcher, such as aterminal, which is under the control of a separate entity. If theboundary element includes uncontrolled track, the LPA s represent theboundary element as a finite capacity queue for planning purposes.

If the boundary element is controlled track, then a queue will notusually be used to represent the constraint by the LPA. Controlledboundary elements are represented by their detailed track structure. Foreach train passing through the controlled boundary element, thesupplying LPA will determine the track segment that the train willutilize and indicate the time that the train will pass through theboundary element. After resolving the conflicts for the boundary, theLCA will specify the precedence relative to other trains utilizing thesame track element. In order to resolve the conflicts, the LCA may delaya train's arrival at the boundary, but may never advance the time ofarrival from that forecast by the LPA in the LMP.

Boundary elements require special consideration because of theindependent nature of the planning processes. An LPA attempts tooptimize the movement of trains within its area of concern. This processwill, if unchecked, attempt to push trains through a planning areawithout regard to the problems caused in an adjacent planning areas orat the boundary element between planning areas. Boundary congestionproblems are addressed by the LPAs by placing limits on the flow oftraffic into a boundary element. The limiting mechanism is the finitecapacity of the boundary element. Restricting the flow across theboundary element provides a control mechanism that may be used to reducethe buildup of congestion in a neighboring area.

In another aspect of the present invention boundary elements betweenplanning areas are chosen so as to minimize the interaction betweenLPAs. For example, the boundary element can be chosen as a terminal,which may be composed of multiple yards represented by a finite capacityqueue. Using a terminal at the boundary point facilitates the hand-offbetween adjacent planning areas because it provides buffer space to holda train at the boundary element between the asynchronously scheduledplanning areas.

FIG. 3 illustrates an example of the application of one embodiment ofthe invention where a terminal has been selected as a boundary element.LPA 1 plans the movement of trains into a suitable LPA 1 receiving yardreferred to as a South receiving yard 36 and accepts trains from asuitable LPA 1 departure yard referred to as a North departure yard 34through a suitable train interlock switch 33. South receiving yard 36and North departure yard 34 are not visible for planning purposes to LPA2. LPA 2 plans the movement of trains into a suitable LPA 2 receivingyard referred to as a North receiving yard 35 and accepts trains from asuitable LPA 2 receiving yard referred to as a South departure yard 37thorough a suitable train interlock switch 33. North receiving yard 35and South departure yard 37 are not visible for planning purposes to LPA1. The run thru queue 30 for the terminal is a boundary element and isvisible to both planning agents as are main lines #1 and #2 at 31 and 32respectively. The boundary element 30 may be represented as two one wayqueues or a bi-directional queue. If the boundary element 30 isrepresented as two finite capacity queues (each with a specifieddirection of movement), then each LPA agent would plan trains to moveinto one of the queues and accept trains from the other queue. If, onthe other hand, a bi-directional queue is specified, then eitherplanning agent may move trains into or accept trains from the queue.Because both planning agents are attempting to move trains into the samequeue, a conflict situation may develop that must be resolved by an LCA.

Boundary element queues for uncontrolled track have a finite capacitythat may vary with time. The capacity of a boundary queue must beallocated among two adjacent LPAs for a planning interval. There areconceptually three means of allocating the capacity, (a) fixedallocation, (b) time dependent allocation, and (c) dynamic allocation.

For fixed allocation, the capacity of the queue for the boundary elementis allocated according to a fixed ratio that is constant. For example, aqueue with capacity of 4 might have capacity of 2 allocated to each ofthe LPAs.

For time dependent allocation, significant traffic variations may bemanaged by allocating the boundary element queue capacity according to afunction of time. For example, if a peak in a first direction (such aswestbound traffic) occurs in the morning hours and a peak in the opposeddirection (such as eastbound traffic) occurs in the evening hours, thenthe boundary element could allocate the capacity to match the trafficpeaks. For example the allocation of queue capacity could be allocatedto provide a capacity of 3 westbound and 1 eastbound in the morning and3 eastbound and 1 westbound in the evening.

With respect to dynamic allocation, maximum utilization of the boundaryqueues may be obtained by dynamically allocating the capacity inaccordance with the current traffic levels. In this case, a LCA wouldautomatically manage the allocation of the boundary queue capacity basedupon the projected need for the queue by each of the LPAs. Fixed anddynamic allocation schemes require the least intervention by users. Inmany situations, variations in traffic make the dynamic allocationscheme attractive. The dynamic allocation approach requires a LCA toperform the allocation of the boundary capacity among the LPAs.

If the boundary element is controlled track then it is advantageous tosimplify the decision process at the boundary. FIG. 4 is an example ofone embodiment of the present invention in which the boundary element isa single controlled track. In an area with single track 40 and sidings42 and 43, it is advantageous to choose a single-track segment 45,rather than choosing a siding as the boundary element. In this case,trains must be sequenced through the boundary element 45. A LCA willdetermine the sequence in which trains will pass through the boundaryelement 45. LPA 1 and LPA 2 will insert a conditional stop for the trainat the last safe location in the schedule to assure that the movementsthrough the boundary element 45 are executed in the proper sequence. Theconditional stop will enforce the order of trains moving through theboundary element 45 by holding a train at a safe place, for example at asiding 42, until the train that precedes it has completed its move.

FIG. 5 illustrates an example of the application of another embodimentof the invention in which the boundary element 55 is controlled multipletrack 50 and 51. The process functions in the same manner as discussedabove. In this case the supplying LPA determines the track that thetrain will use to cross the boundary and the LCA determines the sequenceof trains over each track segment. LPAs insert a conditional stop toenforce the appropriate ordering of train movement through the boundaryelement 55.

One effective means of managing the flow between planning areas is torestrict the separation time between trains. For example, one mightrestrict the boundary element to space trains at least 10 minutes apart.This can be accomplished by the LCA setting the boundary queue capacityto 1 and the processing time to ten minutes.

In operation, one embodiment of the present application provides a dailyschedule for the entire rail network identifying the trains, selectedwaypoints and activity locations and corresponding times of passage,arrival and/or departure from the designated locations of interest.Alternatively, trains may be introduced incrementally into the networkat or prior to their origination. Based upon the identified plurality ofLPAs, the train schedules are partitioned according to the extent of theLPAs and the appropriate portions of the schedule passed to the LPAsprior to entry of the train into the planning area.

Estimated time of arrival (ETA) of a train at waypoints throughout itsjourney are based upon the daily schedule provided. LPAs will refer tothe daily schedule for anticipating the lineup of trains from adjacentLPAs. A daily schedule typically includes an origin point, a destinationpoint, work locations, and other waypoints that must be visited by thetrain. This is expanded in the embodiment to include a detailed routeidentifying every track segment and switch over which the train willpass and is initially populated with ETA's from the network planningfunction and extrapolations of the schedule based upon train performancecalculations. Subsequent updates to ETA's are made by the LPA in whosearea a train is currently being tracked and propagated to remainingelements of a schedule.

Each LPA resolves any movement conflicts within the local planning areaand within the planning horizon based on the initial input of theschedule to provide a LMP. Each LPA operates independently of all otherLPAs and asynchronously of the other LPAs. Each LPA will take adifferent amount of time to generate its LMP and each LMP is submittedto a LCA each time it is completed without regard to the time ofcompletion of other LMPs. Staggering of the operation of the LPAs isbeneficial in that the LPA share access to common resources, i.e.,databases, and the staggering reduces the likelihood of the LPAs tryingto gain access to the common resources at the same time.

Each LPA may generate a LMP periodically, e.g. hourly “generationcycles”, and passes the portion of the movement plan relating to theboundary elements to a LCA. The LPA may have a planning horizon which isconfigurable typically is as long as a typical crew shift, i.e., eighthours. The LCA compares the LMPs from adjacent planning areas sharing acommon boundary element and resolves any conflict with the use of theboundary element. The LCA will determine the movement order constraintsfor the boundary element, i.e., the order of the trains and the rangesof times of arrival and departure for the trains through the boundaryelement. The boundary element constraints are passed to the applicableLPAs to update their respective LMPs consistent with the boundaryelement constraints at the next regularly scheduled update of the LMP.This update cycle normally occurs at frequent intervals (e.g. 4 minuteintervals). While the LPAs control the movement of the trains within itslocal planning area, the order of trains over the boundary element isset by the LCA and may not be independently changed by a LPA.

Each LPA may include a local schedule repairer process, such as thatgenerally described in commonly assigned U.S. Pat. No. 5,623,413 whichis incorporated by reference herein, that updates the LMP based uponperiodic train state update information. The revised ETA's at theboundary element from the revised LMP are typically passed to the LCAand forwarded to the neighboring LPA but the LCA does not revisit thesequence of the trains until the periodic generation cycle (hourly). Thedata relating only to the boundary elements is sent to the LCA aftereach periodic generation of the LMP, independently of the sending ofLMPs from any other LPAs to the LCA. For example, the respective LMPsfor a specific train traveling through adjacent planning areas may havedisagreement at a boundary element hours in advance of the train'sarrival. As a train approaches the boundary element the discrepanciesbetween the LMPs decline in magnitude as the estimates of arrival timeat the boundary become more accurate. Sometime prior to the arrival of atrain at the boundary, the discrepancies between the LMPs have reducedsufficiently and the plan is frozen and LPAs and LCAs will make nofurther change in the plan.

The LPA generates a LMP in two steps, 1) the generation of a completenew LMP by the scheduler process and 2) the refinement of the LMP by theschedule repair process. The scheduler and scheduler process may be ofthe type generally described for example in commonly assigned U.S. Pat.No. 5,623,413 which is incorporated by reference herein.

The scheduler process provides a high-level movement plan for a planningarea. Boundary coordination in the scheduler process will be obtainedfrom the LCA as described above. These constraints include the time thatentering trains will appear at a boundary element and the trackavailability at a boundary element that has been reserved by the LCA forthe adjacent LPA. The output of the scheduler process in the LPA isreferred to as a “coarse schedule”. It is intended to provide anapproximate solution that is refined into a feasible solution in aschedule repair phase.

The schedule repair process removes any remaining constraint violationsbased upon the position of the trains at the time that the LMP isrefined. A coarse schedule defines all track segments that a trainpasses over. Schedule repair in the LPA may, if an alternate track hasbeen made available by the LCA and the track element has not beenfrozen, choose to use an alternate track rather than the elementspecified in the coarse schedule. The LCA will indirectly influence theselection of track assignment by the allocation of track to an adjacentplanning area. The boundary element may require coordination with ayardmaster, a dispatcher from another railroad, or the LPA from anadjacent planning area. In the normal condition, however, nocoordination with a human is required.

The schedule repair of a LMP at a boundary element requires conformanceto the latest LMP as modified by the LCA. The schedule repair processwill seek a repair of the LMP that provides minimum deviation from thecurrent LMP.

The schedule repair process will honor the ordering of trains through aboundary element. For each boundary element, the LCA for the boundaryelement will prepare a schedule for usage of the boundary element basedupon the LMPs generated by the adjacent LPAs. This schedule will be atime ordered schedule of resource usage. During the schedule repairprocess, the LPA will honor the track assignment and train orderspecified in the LMP.

For example, if a Train B is planned to move through the boundaryelement at 1:30 on Main #2 track and a Train A is planned to movethrough the boundary element over Main#2 track at 1:15, the schedulerepair may not move either train to Main#1 track and Train B must followTrain A in using Main#2 track. If Train A is delayed and is not able tomove through the boundary element until 1:35, Train B must be delayeduntil after 1:35. At the “last safe place” before entering a boundaryelement, schedule repair process will insert a special “ConditionalStop” that will hold a train from entering a boundary element until thepreceding train has cleared the boundary element.

In the event that an unexpected event makes it necessary for schedulerepair process to change the ordering through the boundary element, theLPA will cause the appropriate LCA to alter the ordering of the trains.For example, a LMP as confirmed by a LCA established an order for trainsto pass through a boundary element. The ordering provided for Train A toproceed eastbound. After Train A cleared the boundary element, Train Ccould proceed westbound. Once Train C had cleared the boundary element,Train B would proceed eastbound. If an anomalous event, requiring are-ordering of trains, occurs just prior to a boundary element, theschedule repair process will generate and post a repaired plan andrequest a replan by the LCA. The LCA will reconsider the boundaryelement scheduling and compute a new ordering for the trains. Theautomatic issuance of authorities for the trains involved isdiscontinued until a new plan is posted, resolving the conflictingsequence request. In the example, the new sequence may be determined tobe Train B-Train C-Train A. The new sequence is then posted for use bythe LPAs to update their respective LMP's and the automatic issuance ofauthorities resumes.

In the case of hand-off to an adjacent LPA, the hand-off occursautomatically. A hand-off in this situation requires detailedcoordination between the adjacent LPAs. The appropriate track andsequence of movements over the track will be determined by the LCA andwill be followed by the local schedule repairer in each LPA.

FIG. 6 illustrates one aspect of the coordination of the LCA and theLPAs for a train traveling from Planner 1's (LPA1's) territory toPlanner 2's (LPA2's) territory. In FIG. 6, LPA 1 schedules the train(e.g., Train A) to move the train into the boundary element at 60 anddepart the boundary element at 62. LPA 2 schedules the same train tomove the train into the boundary element at 65 and depart the boundaryelement at 67. Thus LPA 1 plans to move Train A into the boundaryelement at 60, ahead of the plan developed by LPA 2 at 65. In this case,the LCA will compute the boundary element dwell time based upon the timethat LPA 1 moves the train into the queue at 60 and the time that LPA 2plans for Train A to depart from the boundary element at time 65.Because the dwell time in the boundary element computed by LCA isgreater than usage time of the boundary element required by the train,the LCA can pass an earlier departure time to LPA2.

FIG. 7, illustrates another aspect of the coordination of the LCA withthe LPAs for a train (e.g., Train B) traveling from planning area 1 toplanning area 2. LPA 1 schedules Train B to move the train into theboundary element at 74 and depart the boundary element at 76. LPA 2schedules Train B to move the train into the boundary element at 77 anddepart the boundary element at 79. Thus LPA 1 plans to move Train B intothe boundary element at 74 behind the plan developed by LPA 2 at 77. Inthis case, the boundary element dwell time constraint is violated. Thissituation occurs when LPA 1 changes the ETA of Train B because of anunexpected delay from the time previously provided to LPA 2. For thesecases, LPA 1 does not move Train B into the boundary element earlyenough to complete its work before LPA 2 has scheduled Train B todepart. The LCA will recognize this as a conflict in the train'smovement plan. The coordinating agent will pass the new ETA from LPA 1to LPA 2 and adjust the ETD appropriately in order to identify any otherconflicts induced by the change.

ETA's between updates will vary because of changes in the LMP developedby a LPA. As a train approaches a boundary point, the forecasted ETAwill become more accurate and the ETA's used by each LPA will converge.In addition the plan will be frozen as the trains near the boundaryelement to preclude last minute changes to the plan. Additionalconflicts in usage may occur because a LPA holds a train in the boundaryelement. For example, a LPA may plan to hold train in a boundary elementfor an additional thirty minutes in order to improve the flow in itslocal planning area. This hold will preclude the adjacent LPA fromforwarding another train into the boundary element. This affect willslow the transfer of traffic toward the boundary point.

Overbooking of a boundary element (exceeding the capacity of theboundary element) may occur because of the asynchronous and independentnature of the LPAs. The cognizant LCA will examine the LMPs from therespective LPAs and remove the overbooking by delaying the plannedarrival of selected trains. The LCA will utilize the business objectivefunction associated with each train to incur the least impact to thevalue of the objective function.

With respect to FIG. 8, in operation, the LCA may first build a resourceusage data structure at resource usage database module 80 based upon theresolved arrival and departure times for the trains in the LMP asdescribed above. Unanticipated events may cause random delays in arrivaltimes. In order to minimize the impact of such variations, a LCA willinclude cushion in the planned usage of the boundary queue. The cushionwill be a function of the “time to arrival” for the train. For example,a train scheduled to arrive in one hour might have a 5-minute cushion inits arrival time, whereas a train scheduled to arrive in two hours mighthave a 10-minute cushion. The amount of cushion provided is a userconfigurable parameter. This cushion reduces the wasted capacity thatmay occur because of random variations from the movement plan.

The LCA will next scan through the usage data to identify the earliestoverbooking interval at overbooking detection module at 82. Once theearliest overbooking interval is identified, the LCA identifies thosetrains that are involved in the overbooking and selects a train to delayin order to reduce the overbooking in overbooking elimination module 83.The selection is made based upon the business objective functionassociated with each candidate train. The selected train is delayed atmodify movement module 84 and the LCA then repeats the loop to identifyand remove any remaining overbooking. When all overbooking is eliminateda final sweep is performed to eliminate any unnecessary delay introducedby the LCA at eliminate delay module 85 and the results are sent to therespective LPAs at 86.

In the event of the detection by the LCA of an unacceptable conflictbetween the LMPs at any boundary element, the conflict is passed to ahuman dispatcher for resolution. The LCA provides each LPA with revisedconstraints for each boundary element without any regard to conflictswhich may have been previously resolved by the LPA, or which may begenerated within any local planning area due to the revised constraints.

Each of the LPAs revises its LMP consistent with the updated data on thetrain's (a) location and state and (b) the revised boundary elementconstraints from the LCA, and provides a revised LMP to the LCAperiodically. The LCA compares the received LMPs currently available toit without regard to when such plans were received, and repeats theprocess of revising the boundary constraints.

The LMPs are implemented with the assistance of human dispatchers. Thenetwork of track is divided into a plurality of dispatch areas where ahuman dispatcher is normally responsible for the traffic through hisdispatch area. A dispatch area typically does not correspond to thelocal planning areas and generally a local planning area encompassesseveral dispatch areas. Thus a dispatch area uses only a portion of theLMP corresponding to that dispatch area. The LMPs are automaticallyimplemented in coded track coverage (“CTC”) territory, switches arepositioned automatically, signals cleared in advance of the train, andthe assistance of a dispatcher is required only when a conflict can notbe resolved by the LPA/LCA. The dispatcher generally has moreinformation at his disposal than the LPA/LCA and thus the dispatcher isable to resolve a conflict using information not available to theLPA/LCA. As such, the movement plan provided to the dispatcher allowsthe dispatcher to evaluate the inputs and make adjustments wherenecessary. In track warrant control (TWC) territory a dispatcher isnotified when a track warrant should be issued based upon the LMP.Dispatcher issuance of a track warrant following the proper proceduresis required.

This arrangement allows the dispatcher to “dispatch by exception” in CTCterritory, requiring the dispatcher to take action only when the LCAidentifies a conflict that can not be resolved by the LCA. The systemdescribed above presents a unique interface and software applications toassist the dispatcher to fulfilling his duties. For example, a task listis generated which identifies actions requiring the dispatcher'sattention. Other applications assist the dispatcher in establishingcommunications with the trains in his dispatch area and allowing themodification of waypoints and activity locations. The above functions ofthe LPA and the LCA can be implemented using computer-usable mediumhaving a computer readable code executed by special purpose or generalpurpose computers.

While preferred embodiments of the present invention have beendescribed, it is understood that the embodiments described areillustrative only and the scope of the invention is to be defined solelyby the appended claims when accorded a full range of equivalence, manyvariations and modifications naturally occurring to those of skill inthe art from a perusal hereof.

1. A method of controlling the movement of plural trains along a networkof track, comprising: (a) dividing the network into plural planningareas, with each planning area of a pair of adjacent planning areassharing at least one common boundary element on track common to theadjacent planning area; (b) developing a local movement plan for eachplanning area independently of the movement plan for other planningareas to control the movement of trains into and out of the commonboundary element associated with the planning area; and (c) evaluatingthe local movement plans for adjacent planning areas to identifyconflicts at the respective boundary element, wherein said dividing thenetwork into planning areas includes dividing the network as a functionof the amount of proposed traffic for the track of each planning area.2. A method of controlling the movement of plural trains along a networkof track, comprising: (a) dividing the network into plural planningareas, with each planning area of a pair of adjacent planning areassharing at least one common boundary element on track common to saidadjacent planning area; (b) developing a local movement plan for eachplanning area independently of the movement plan for other planningareas to control the movement of trains into and out of the commonboundary element associated with the planning area; and (c) evaluatingthe local movement plans for adjacent planning areas to identifyconflicts at the respective boundary element, wherein a planning timehorizon of each local movement plan is approximately eight hours.
 3. Themethod of claim 2 wherein each local movement plan is updatedapproximately hourly.
 4. A method of scheduling the movement of pluraltrains along a network of track, comprising: (a) dividing up the networkinto a plurality of planning areas separated by boundary elements, witheach boundary elements comprising a portion of the network of trackwhich is common to respective planning areas; (b) generating a movementplan for each planning area independently of other planning areas tocontrol the movement of trains into and out of the boundary elements;and (c) evaluating each of the movement plans and identifying schedulingconflicts at respective boundary elements, wherein said evaluating eachof the movement plans includes: (d) assigning a business objectivefunction for each of the trains in the planning area; (e) evaluating thebusiness objective functions for each of the trains; and (f) identifyinga capacity of the boundary element, constraints on occupancy times andthe planned usage of the specified boundary element from each of theplanning areas.
 5. The method of claim 4 wherein said modifying themovement plan includes: (g) providing movement order constraints foreach boundary element; and (h) providing an order for the trains to movethrough the boundary element.
 6. A method of providing a detailed trainmovement plan for controlling the travel of plural trains of pluralcomponents along an interconnected network of tracks across a globalplanning area comprising: (a) dividing the global planning area intoplural local planning areas each including a portion of the network oftracks, the boundaries of adjacent local planning areas being crossed atpoints of network transition having common boundary elements; (b)providing a daily schedule for all trains transiting the network, thedaily schedule providing waypoints and activity locations and time ofarrival and departure at, each of the waypoint and activity locations;(c) providing a local movement plan (“LMP”) for each of the plural localmovement areas revising the times of arrival and departure at thewaypoints and activity locations to attempt to resolve all of theconflicts as to the usage of the portion of the network and traincomponents within a local area independently of the resolution of anysuch conflicts in any other local area; (d) comparing the LMPs havingcommon boundary elements and resolving any conflicts in the commonboundary elements by revising the LMPs.
 7. The method of claim 6 furtherincluding: (i) independently monitoring the actual movement of traincomponents over the network within each of the local planning areas; and(ii) periodically updating each of the LMPs as a function of themonitored movement of train components.
 8. The method of claim 7 furthercomprising: (i) comparing the updated LMP from each of the local areaswith common boundary elements: (1) periodically; and/or (2) each timethe LMP is updated.
 9. The method of claim 6 wherein said dividingcomprises dividing the global planning area into plural local planningareas as a function of the amount of track included within the localarea and the amount of proposed traffic for such included track.
 10. Themethod of claim 6 wherein said comparing the LMPs includes the step ofidentifying a conflict which can not be resolved.
 11. A method ofscheduling the movement of plural trains along a network of track,wherein the network is divided into a plurality of planning areas,comprising: (a) selecting the size of each planning area as a functionof the amount of track and amount of proposed train traffic along thetrack in the planning area; and (b) selecting the boundaries as afunction of the portions of the network of track which is common toadjacent planning areas.
 12. The method of claim 11 wherein saiddeveloping a movement plan is performed independently for each planningarea.
 13. The method of claim 11, further comprising: (c) developing amovement plan for each planning area.